Date: Tue, 10 Dec 1996 03:21:29 GMT
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	<title>Presentation of Simulation Results </title>
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<!WA0><img src=http://www.cs.washington.edu/research/projects/lis/chaos/www/chaos.xbm> <p>

<h1> <a name="top">Presentation of Simulation Results</a><br>
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<p>
<hr> <p>

Because the format of presentation of simulation (or experimental) results in
network routing studies varies greatly, we present these pages as a
suggestion of standard presentation formats.  The formats were inspired by 
discussion at <!WA1><a href=http://www.cs.washington.edu/research/projects/lis/chaos/www/pcrcw.html> PCRCW '94 </a>.

There were two main issues discussed:
<ul>
<li> Units used to label the X-axis 
<li> General form of the presented graph(s)
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<p><hr><p>
<h1> Graph Format </h1>
Two formats were suggested for graphing results.  Paired throughput vs. applied load and latency
vs. applied load comprise <!WA2><a href=http://www.cs.washington.edu/research/projects/lis/chaos/www/cnf.html> Chaos Normal Form.</a>  A single latency vs. 
achieved throughput graph makes <!WA3><a href=http://www.cs.washington.edu/research/projects/lis/chaos/www/bnf.html> Burton Normal Form.</a>

Use of only latency (including source queueing) vs. applied load is discouraged because 
it is impossible to gain any data about performance above saturation using such graphs.

<p><hr><p>
<h1> Units for Bandwidth/Load </h1>

The literature describing results typically includes graphs of latency or throughput
vs. applied load.  Many units have been used to express this, including flits injected/cycle,
flits/ns, bits/cycle, normalized bandwidth, and many others.  Because the many forms
require conversions to compare with other results, we propose using a single form:  <em> normalized
bandwidth. </em>
<p>
Normalized bandwidth simply expresses the load/throughput as a fraction of the bisection-bandwidth
limited maximum bandwidth of the network for uniform random traffic.  Essentially, this constraint,
corresponding to normalized throughput = 1.0, is derived by considering that 50% of uniform random
traffic crosses the bisection of the network.  Thus, if a network has bisection bandwidth B bits/sec, each 
node in an N-node network can inject 2B/N bits/sec at the maximum load.  An optimal routing 
algorithm could handle such a load without before saturating.
<p>
Non-uniform or non-random traffic patterns may saturate at different loads than uniform random traffic.
However, please normalize to the uniform random traffic limit.

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<!WA4><a href="http://www.cs.washington.edu/research/projects/lis/chaos/www/chaos.html"><!WA5><img src=http://www.cs.washington.edu/research/projects/lis/chaos/www/chaos.xbm></a> Back to the Chaotic Routing Home Page <p>

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<address>
kwb@cs.washington.edu
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